Harold Zirin, 82

Harold Zirin, a leading figure in solar astronomy and professor of astrophysics, emeritus, at Caltech, passed away on January 3. He was 82.

Zirin was a pioneer in nearly all areas of solar astronomy, including solar radio astronomy. In particular, he made significant contributions to the understanding of the sun's magnetic field in the solar atmosphere, solar flares, massive loops of hot plasma called prominences, and active regions on the sun's surface. With more than 250 research papers to his name, Zirin also mentored numerous students and postdocs who are now leaders in the field.

In the late 1960's, Zirin led the construction of Big Bear Solar Observatory (BBSO) on Big Bear Lake in California. The BBSO, which was operated by Caltech under Zirin's direction until it was transferred to the New Jersey Institute of Technology in 1997, was-and remains to this day-one of the world's most productive solar observatories.

"He was a pillar of the solar community," says Ken Libbrecht, a professor of physics who worked with Zirin for 15 years. "When people think of Hal, they think of Big Bear Solar Observatory. He conceived it, he built it, and he turned it into one of the world's preeminent solar observatories."

Born in 1929 in Boston to a mother from Galicia, in Eastern Europe, and a father from Russia, Zirin was raised in the Bronx in New York City and then in Bridgeport, Connecticut. His father sometimes sold potatoes and vegetables on the street in New York, and in Bridgeport he worked at a furniture factory. But as a member of the communist party, his father was most passionate about politics and revolution, Zirin said in his oral history. "Some of my earliest memories are of being taken to party meetings," he recounted.

Zirin's interest in astronomy began in the eighth grade, when he first glimpsed the craters of the moon in detail. "I was 12 or 13 years old," he recalled. "One of the kids in the class had a telescope, so we went to his house and looked through his telescope at the moon. When I saw that, I remember saying, 'I want to be an astronomer.'"

A stellar student, Zirin built a telescope in high school that earned him a top-10 finish in the Westinghouse Science Talent Search, which drew the attention of Harvard University. Famed astronomer Bart Bok recruited him, and he earned his bachelor's degree from Harvard in 1950. He stayed for graduate school and received a master's degree in 1951 and his PhD just two years later.

After graduation, Zirin left the East Coast for California to work for the RAND Corporation, but was only able to stay for a year. With the Cold War rearing up, his father's past communist activities prevented him from receiving security clearance. Zirin was accused of attending a communist party meeting-when he was 11 years old. He then returned to Harvard as a research fellow and lecturer. In 1955, he joined the research staff at the High Altitude Observatory in Boulder, Colorado, where he began the research in solar astronomy that would define his career.

In Colorado, he met Mary Fleming, who became his wife in 1961. The couple soon adopted a son and daughter. In 1964, he became a professor of astrophysics at Caltech, where he would remain until retirement in 1998. Mary taught Russian at Caltech from 1969 to 1973.

In addition to his work at BBSO, Zirin led the solar-astronomy research efforts at Caltech's Owens Valley Radio Observatory in the 1970s and developed the observatory's solar interferometer. While other fields in astronomy like cosmology became more popular, Zirin remained passionate about the sun, earning the nickname Captain Corona from his students and colleagues. His students depicted Captain Corona as a comic-book character, a mild-mannered professor who transformed into a caped superhero when he entered a solar observatory.

"He loved the sun," says Libbrecht, who adds that Zirin had a bit of an antiestablishment personality. "Hal liked to stir things up," he says. "He liked to speak his mind." In addition to his many research papers, Zirin wrote two textbooks on solar astronomy, The Solar Atmosphere and Astrophysics of the Sun. Libbrecht adds, "He was a good person, an excellent scientist, and for a generation he was a central figure in solar astronomy."

Zirin is survived by his wife, Mary; son, Daniel; daughter, Dana Haigney; and two grandsons, William and Jacob. The family asks that donations be made in Zirin's name to National Jewish Health in Denver, Colorado.